Coronavirus

From Cow
Bovine coronavirus
Intensive therapy in a calf infected with bovine coronavirus

Bovine coronavirus is an enveloped, single stranded RNA virus found worldwide.

This virus is genetically related to canine respiratory coronavirus.

Bovine coronavirus is incriminated in scours in calves as well as Bovine respiratory disease[1]. Coronavirus is a pneumoenteric virus that causes mild or severe respiratory infections and severe lower intestinal infections with enteritis[2]. Enteric disease is often seen in combination with respiratory clinical signs[3]. In addition to causing diarrhea in young calves, it is associated with winter dysentery in cows.

Coronavirus is particularly common in 4 - 30 day old calves[4] and is seen most commonly in calves approximately 1 week of age which is the time when antibody levels in the dam’s milk starts to wane and calf exposure is maximal[5]. Disease due to coronavirus is most common during the winter months which may reflect the enhanced survival of the virus in a cool, moist environment. One study shows that the incidence of coronavirus is 8 - 69% in diarrheic calves, and 0-24% in healthy calves[6].

Clinical signs

The diarrhea caused by coronavirus usually lasts 4-5 days[7]. There is rapid loss of water and electrolytes. Glucose and lactose metabolism are also affected resulting in hypoglycemia, lactic acidosis and hypervolemia which can lead to acute shock, cardiac failure and death. Experimental infection of calves has resulted in depletion of lymphocytes in the mesenteric lymph nodes and Peyer’s patches, low levels of immunoglobulins and generalized immune suppression

Diagnosis

Diagnosis of bovine coronaviral infections can be accurately determined using modern PCR testing of fecal or respiratory samples[8].

Treatment

Treatment of infected calves and cattle is usually symptomatic and supportive. Intravenous fluid therapy is often required in valuable calves and cattle.

References

  1. Merck Veterinary Manual
  2. Thomas, CJ et al (2006) Transmission of bovine coronavirus and serologic responses in feedlot calves under field conditions. Am J Vet Res 67:1412
  3. Liu, LS et al (2006) Molecular epidemiology of bovine coronavirus on the basis of comparative analyses of the S gene. J Clin Micro 44:957
  4. Naylor, JM (2002) Neonatal Ruminant Diarrhea, p:355-356. In B. P. Smith (ed.), Large animal internal medicine. Mosby, St. Louis
  5. Murphy, FA et al (1999) Coronaviridae, p. 501-502. In Veterinary Virology. Academic, San Diego, California
  6. Radostits, OM (2000) Viral diseases characterized by alimentary tract signs, p:1116-1120. In Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses. Saunders, London
  7. Murphy, FA et al (1999) Coronaviridae, pp:501-502. In Veterinary Virology. Academic, San Diego, California
  8. Fukuda M et al (2012) Development and application of one-step multiplex reverse transcription PCR for simultaneous detection of five diarrheal viruses in adult cattle. Arch Virol 157(6):1063-1069